In March 2007, PUBPAT filed formal requests with the United States Patent and Trademark Office challenging four key HIV/AIDS drug patents held by Gilead Sciences, Inc. (NASDAQ: GILD). As part of its requests, PUBPAT submitted prior art that the Patent Office did not review before granting the patents to the Foster City, California, biopharmaceutical giant. PUBPAT also explained how the submitted prior art invalidates the patents and asked that the Patent Office undertake a review and revoke them. In July 2007, the Patent Office granted each of PUBPAT's requests and ordered reexamination of all four patents. In December 2007 and January 2008, the Patent Office rejected all of the claims of each of the patents.